1. Field of the Invention
The present invention relates to division masks used in depositing thin films and methods of assembling mask frame assemblies by using the division masks.
2. Description of the Related Art
In general, among display devices, organic light-emitting display devices have wide viewing angles, excellent contrast, and quick response speeds.
In an organic-light emitting display device, light is emitted by the recombination of holes and electrons which are injected into an anode and a cathode. The organic-light emitting display device has a stack structure in which the emissive layer is inserted between the anode and the cathode. However, since it is difficult for an organic-light emitting display device having this structure to have high luminescent efficiency, an electron injection layer, an electron transfer layer, a hole transfer layer, a hole injection layer and the like are selectively inserted between the emissive layer and each of the anode and the cathode.
Electrodes and intermediate layers, including an emissive layer of an organic-light emitting display device, are formed by using various methods. One of the methods is a deposition method. In order to manufacture an organic-light emitting display device by using the deposition method, a fine metal mask (FMM) having the same patterns as those of a thin film to be formed on a substrate is aligned on the substrate, and then the thin film having desired patterns is formed by depositing a raw material of the thin film.
As the FMM is large in size, more etching errors occur, and a central portion of the FMM is likely to sag due to its weight. Thus, recently, a division mask, formed by forming various mask sticks and attaching the mask sticks onto a frame, has been widely used.
However, the division mask is large in size, having a length of about 1,840 mm in order to satisfy the users' requirements of a large-size display device. Thus, creases may be formed lengthwise in each division mask. That is, as each division mask is long in size, creases may be formed on the division mask, and the division mask is not consistently flat. In this case, various problems may occur also in a deposition process in which fine patterns are to be formed by using the division mask.
Thus, there is a need to prevent creases from being formed on the division mask.